Elevator safety device.



R. C. SMITH.

ELEVATOE SAFETY DEVICE.

APPLICATION FILED NOV.f28, 1905.

Patented Feb. 6, 1912.

2 SHEETS-SHEET 1.

R. C. SMITH.

ELEVATOR SAFETY DEVICE.

APPLIGATIQN FILED Nov. 2s, 1905.

2 SHEETS-SHEET 2.

coLUMBlA PLANOURAPH Cfr-.WASHINGTON D C Patented Feb. 6, 1912.

III

RUDOLPH C. SMITH, 0F YONKERS, NEW YORK, ASSIGNOR T0 OTIS ELEVATOR COMPANY, OF JERSEY CITY, NEW JERSEY, A CORFOlEt/ATION OF NEW JERSEY.

ELEVATQR SAFETY DEVICE.

Application filed November 28, 1905.

To all whom t may concern:

Be it known that I, RUDOLPH C. SMITH, a citizen of the United States, residing at Yonkers, in the county of lVestchester and State of New York, have invented a new and useful Improvement in Elevator Safety Devices, of which the following is a specification.

My invention relates to elevator safety devices, and one of its objects is the provision of simple and efficient means for gradually retarding an elevator car and stopping the same with minimum shock or jar.

A further object of the present invention, is the provision of means for positively actuating a safety device to gradually stop a carl within a predetermined distance of travel.

Other objects of the invention will appear hereinafter, the novel combinations of elements being pointed out in the claims.

In the accompanying drawings, Figure 1 represents an elevator car with my improved safety device attached thereto; Fig. 2 represents a bottom plan view of the safety device of Fig. 1; Fig. 3 illustrates a means for holding the drum of the safety in position; Figs. 4 and 5 show in detail the actuating cam to move the clamps into engagement with the -guide rails; Fig. 6 shows a friction device for preventing certain parts from being moved when the cam is initially actuated; Fig. 7 illustrates a modification; and Fig. 8 illustrates diagrammatically the governor mechanism for automatically affecting the operation of the safety device when the car speed is excessive.

In Fig. 1 is shown an elevator car 1, beneath the floor of which is suitably mounted my improved safety device. `Wedge clamps pivoted at 4, 4 and comprising clamping jaws 6, 6 and 7 7 are adapted to engage the stationary guides or T-rails 5, 5 and thus effect a stopping of the car. Normally the jaws should preferably be held wholly out of engagement with said guides by means of compression springs 40, 40 bearing against wedges 19 acting on the lever arms 8, 8 and 9, 9 of the clamping apparatus. rIhis being of well known construction, however, it is not disclosed in detail.

Rotatably mounted intermediate the clamps on bearings such as shown at 13, 13', is the safety drum 10 on which the governor rope 11 (Fig. 8) is wound one or more Speccaton of Letters Patent.

Patented Feb. 6, 1912.

Serial No. 289,431.

times. If desired the drum may be grooved to receive said rope, but the latter is preferably only in frictional engagement with the drum. Connected to the interior of the drum by means of a key 41, Fig. 4, is a V- shaped cam 12 shown in detail in Fig. 5. This cam may be loosely connected to the drum or rigidly secured thereto, or it may be integral with the drum. It may also be connected to the drum through intermediate means as gearing, for example. Although Fig. 4 illustrates this cam extending through an arc of a little more than 180o, this arc may be varied as desired and furthermore the particular shape of the cam may also be varied without changing the principle of my invention. Also within the .drum 10 and in close proximity to the cam 12, are traveling nuts 14, 14 which are here shown in the form of sleeves. The inner ends of these sleeves opposite the sides 115. 15 of the cam 12 preferably conform in shape to said cam, so that said ends may be substantially parallel with said sides and at a short distance therefrom throughout when the safety is set. rIhe peripheries of the inner ends of the sleeves are in loose frictional engagement with the interior of the drum 10 so that when said sleeves are actuated longitudinally outward they will be properly guided. The outer ends of the sleeves are adapted to slide back and forth in the cylindrical interiors of the drum bearings 13, 13. The latter are rigidly secured to the beams 16, 16 by suitable supports such as shown at 17, 17.

Both sets of clamping jaws and the connections between the same and right and left handed screws 18, 18 may be considered in its entirety a clamping device, or each set and its connections may be termed a clamping device. Normally, the sleeves and the screws 18, 18 are in frictional engagement with each other and move together when the cam 12 is rotated to move the clamping l devices quickly into engagement with the guide rails. The combination with the sleeve and its screw forms a differential screw having a high pitch thread which is the inner face of the sleeve, and a low pitch thread which forms the screw in this instance rigidly connected to the wedge which operates one set of clamping jaws. W'hen the cam 12 is rotated it engages the threads of high pitch and positively moves the the screw. of high pitch, the screw of low pitch, the wedge and interconnect-ing rod. It will therefore be seen that I have provided a high pitch screw arranged to move the clamping device against the guides and a low pitch screw arranged to tighten the clamping device on the guides.

The sleeves 14, 14 are internally screwthreaded to form nuts or rotary cams which fit over the screws 18, 18 to the outer ends of which are secured the wedges 19, 19 for operating the clamps. Intermediate the wedges 19, 19 and screws 18, 18 are suitable guides to direct the wedges longitudinally outward or inward. In this instance.

I have shown slots 20, 20 and 20, 20 in extensions of the drum bearings, in which slots are adapted to slide projections or pins 21, 21 and 21, 21 extending diametrically opposite each other through the bodies of the drum screws 18, 18.

In order to hold the sleeves in proper position, I prefer the construction shown in detail in Fig. 6 although other means for accomplishing this purpose could be devised. As here shown a spring-pressed friction pawl 22 lits into one of the V-grooves 23 in the periphery of the sleeve so that some force must be exerted on the sleeve before it can force the pawl out of the groove and rotate said sleeve. There may be a plurality` of these grooves on both sleeves and of course a friction pawl should be provided for each. The tension of the spring 25 acting on the pawl 22 may be adjusted by means of the screw cap 24.

In a modified construction as shown in Fig. 7 hard metal balls 42 may be placed between the sides 15, 15 of the cam 12 and the inner ends of the sleeves. IVith either arrangement a rotation of the drum 10 independently of the sleeves is assured. It has been found in practice, however, that the balls are unnecessary and I therefore prefer the construction illustrated in Figs. 1 to 6.

After the drum has been rotated to stop the car, as hereinafter explained, its backward rotation is prevented by a springpressed pawl 27 acting on a ratchet 28 of a wheel 29 rigidly secured to the drum 10 or made integral therewith. In order to enable the druln to be rotated in resetting, the right-hand end of said drum is provided with bevel gear teeth 30 which are always in mesh with a small bevel gear 31 directly beneath the floor of the car. A key 32 may be inserted through the floor of the car to turn the gear 31 and consequently the drum 31 in either direction; that is, to effect the operation of the safety device to stop the car as desired or to rotate the drum back to its original position in resetting the same. In the latter case, however, the pawl 27 must also be held in releasing position.

In Fig. 8 I have shown an ordinary governor at the top of the elevator well. Around the sheave 33 of the governor passes an endless rope 11 which is held taut by means of the weight 34 and sheave 35 at the bottom of the well. The governor rope has the usual yielding connection with the car 1 at 36 and then passes over directing pulleys 37, 38 mounted on the lower portion of the car and thence one or more times around the safety drum 10 on t-he bottom of the car.

The operation of my improved safety device may be understood from the following explanation. Normally the governor rope travels with the car and rotatesthe sheaves at the top and bottom of the well and also the centrifugal governor mechanism. lVhen the car speed exceeds a predetermined limit or becomes excessive the governor operates the gripping device 39 to hold the governor rope stationary. The car continues to move to disconnect itself from the rope at 36, and therefore the safety drumy 10 will begin to revolve. The motion of the drum 10 begins substantially at the same time that the governor rope is gripped and the cam 12 immediately wedges in between the sleeves 14, 14 to force the same apart. The sleeves are moved bodily and longitudinally in an outward direction and so also the screws 18, 18 with t-he wedges 19, 19. The clamps are therefore moved into engagement with the guides immediately after the governor mechanism above the elevator well operates to grip the governor rope. It is during this preliminary operation of moving the clamps, that it is desired that the sleeves 14, 14 shall not rotate and this is accomplished by providing anti-friction balls 42 between the cam 12 and the inner ends of the sleeves as shown in Fig. 7, or the construction shown in Figs. 2 and 6 may be used. The relative widths of the ends of the cam 12 may be varied as desired and the distance between the sides 15, 15

and the inner ends of the sleeves 14, 14 may be predetermined so that the jaws 6, 6 and 7, 7 shall engage with the guide rails 5, 5

within a predetermined time after the gov-` ernor grips the governor rope. The spaces between the cam 12 and the sleeves 14, 14 z' may be made adjustable by having a plurality of grooves Q3. As soon as the clamps are thus brought into firm engagement with the guides and the sleeves cannot be moved bodily outward any farther, the frictional engagement between the cam 12 and the sleeves causes the latter to rotate with the drum 10. The sleeves 14, 141 will therefore be turned as nuts or rotary cams on the right and left-handed screws 18, 18, respectively, to move the wedges 19, 19 outwardly still farther and transmit gradually increasing clamping power to the jaws 6, 6 and 7, 7. rIhe projections 21, 21 and 21, 21 sliding in the slots 20, 2O and 20', 20, respectively, prevent the screws 18, 18 from rotating but limit their motion to a longitudinal one. After the governor has once operated to set the drum 10 in motion, the latter will rotate until the car has stopped. In order to prevent the release of the clamps, should the governor rope break, for example, I provide the pawl and ratchet mechanism shown in Fig. 3 where the pawl 27 is pivoted on the framework of the safety device and the wheel 29 having the ratchet 28- in its periphery being rigidly secured to the drum 10. It is therefore evident that when the governor mechanism grips the rope 11, the drum 10 is rotated by the continued motion of the car, and that the clamps are at once positively moved into engagement with guide rails and this may be during a certain distance of car travel. After this operation the further actuation of the drums causes the clamps to be operated with gradually increasing power to bring the car gradually and positively to a stop with minimum shock or jar and also, if desired, within a predetermined distance.

It should be particularly noted that the power exerted by the drum and screw mechanism may be limited and regulated by the weight attached to the lower sheave around which the governor rope passes, or by the number of turns of the governor rope around the drum, or by both. Since the governor rope is not fastened to the drum 10 but merely in frictional engagement therewith, it will slip upon the tension eX- erted on the governor rope reaching a predetermined value less than what would injure the rope. For instance, after full power has been exerted to tighten the clamps onto the guides, the car by reason of a heavy load may continue to move a short distance farther tending to put an excessive strain on the governor rope. In order to prevent breakage of the rope, therefore, I arrange the apparatus so that the governor rope shall slip on the drum at this time.

It is obvious that those skilled in the art may make various changes in the details and arrangement of parts without departing from the spirit and scope of my inven tion, and I desire therefore not to be limited to the precise construction disclosed.

Having thus described my invention, what I claim and desire to have protected by Letters Patent of the United States is:

1. In a safety device for elevators, the combination with a rotatable drum, of a wedge cam connected loosely to said drum, sleeves engaged by said cam, friction devices for preventing said sleeves from turning initially, right and left-hand screws engaged by said sleeves, and clamping devices connected to said screws.

2. In a safety device for elevators, the combination with high and low pitch screws and means for operating them, of a friction device for causing the high pitch screw to move longitudinally initially, clamping apparatus, and pawl and ratchet mechanism to prevent backward rotation of the high pitch screw when the clamping apparatus meets suicient resistance. l

3. In a safety device for elevators, the combination with a safety drum, of a cam located within the drum, a clamping device, and differential mechanism between said cam and clamping device for operating the latter.

4. In a safety device for elevators, the combination with a safety drum, of a rotary cam member operated by said drum, a device for yieldingly holding said member against rotation but permitting a longitudinal movement thereof, a brake, and operating connections between the brake and said cam member.

5. In a safety device for elevators, the

combination with a member adapted for longitudinal and rotary movement, means for applying a combined longitudinal and turning force to said member, a device for yieldingly resisting the rotation of said member, and braking mechanism operated by said member. 6. In a safety device, the combination with a safety drum, of a longitudinally movable rotary cam member, a device for yieldingly preventing the rotation of said member, and clamping apparatus operated by said cam member.

7. In a safety device, the combination with a longitudinally movable, non-rotatable member, of a rotatable member having a screw-threaded connection with and also movable longitudinally with said non-rotatable member, means for yieldingly opposing the rotation of said rotatable member, means for effecting a successive longitudinal and rotary movement of said rotatable member, and clamping apparatus operated by said non-rotatable member.

8. In a safety device, the combination with a safety drum, of a sleeve, a rod having a threaded connection with the sleeve, means independent of said threaded conof the rod, and clamping mechanism oper- 10 ated by the rod.

In testimony whereof, I have signed my name to this specification in the presence ot' tvvo subscribing witnesses.

RUDOLPH C. SMITH. Witnesses W. H. BRADY, EDMUND E. FIELD, Jr.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

